Thousands of objects are transported around the world every day. Most such objects are packaged before transport and grouped together to form larger objects to be placed on or in pallets, shipping containers or the like. Those larger objects are then transported from one place to another by moving means such as planes, trains, trucks, ships or the like. When such objects are being transported, in particular over long distances, the objects may become dislodged due to movement in transit. The object if dislodged may break or be damaged which is undesirable. Accordingly, it has become necessary to secure the objects to a fixed structure, such as the deck of a ship, flatbed of a truck or the like, during transit.
Referring particularly, but not exclusively to shipping, it is common to transport objects in shipping containers. To inhibit movement during transit, a lashing system is typically used to secure shipping containers to the deck of the ship. This helps limit movement of the containers as the ship rolls about during sailing. Lashing systems stabilise the lower rows of containers so that other containers may be stacked on top.
There are however many problems with the existing lashing methods and devices. For example, in most container ports more than 30% of injuries are related to the task of lashing. Lashing workers are performing heavy, awkward work, frequently on an exposed, often slippery deck. The environment is constantly changing, difficult to supervise and dangerous. A delay between the time a ship arrives and the time of the first container being unloaded is an issue for ship owners. This is often due to the time taken to unlash enough containers before the crane can start work safely to unload the containers. The pressure to get containers unlashed therefore results in hurrying and frequently in injury and even death. There is similar (and possibly greater) pressure to complete lashing after the last container is loaded so the ship can set sail on time.
Lashing equipment is by its nature quite heavy. Existing systems can include a rod assembly weighing upwards of 24 kg. This weight combined with a rods length and shape makes them awkward to handle. To make the task more manageable recently components have been designed to be disconnected so that smaller sub-assemblies can be handled one at a time. This results in a process where the majority of the physical effort and time is related to handling lashing components. Also with existing lashing equipment container height and ship variability is not considered. Containers are of different heights. The lashing therefore needs to be adjusted to suit each combination of containers.
Also International guidelines require that lashing is assembled using at least two workers. This adds to the ship owners cost and while reducing the chance of strain through overloading a worker, adds to the risk of one worker striking another by accident in a space constrained deck. This is made worse by the need for the lashing rods to be attached in a way that allows associated turnbuckles to be rotated. This extra clearance requires the rods to be set out at an angle from the container face. The deck on many ships becomes cluttered by lashing encroaching on walkways. The accepted minimum for walkways is now 750 mm between container faces. This is to provide sufficient room for workers to perform tasks. By contrast in some ships the lashing is attached in such a way that the workers must lean across to handle the lashing, increasing the chance of back strain and also of losing balance and causing an accident.
After removal, the lashing is generally stored on deck. In some ships this is done neatly in dedicated bins and racks, in others it results in bars being stored on walkways creating slip and trip hazards. The deck environment and location is not conducive to good maintenance. Lashing should be regularly checked and lubricated. On many ships this results in poorly maintained bars (bent, rusted, worn etc). Removal of a faulty component results in an awkward and physically arduous process to remove and replace the component. The result of this is that faulty or suspect equipment remains in service when it should be removed for repair/replacement. Lashing plans (the number and position of lashings bars) is varied depending on load and expected weather. The high workload of attaching lashing means that ship owners and stevedores seek to use the minimum amount of lashing. This in itself is not a problem but when extra lashing is required (e.g. bad weather expected) it results in a need to carry extra lashing up onto the deck (either up a ladder or even passing the bars around the outside of the ship) this is heavy and difficult work. In some cases where conditions change it can result in the crew having to do this while at sea which is extremely dangerous.
As mentioned above typical lashing is tensioned by use of a bottle screw (or turnbuckle). These turnbuckles are large and heavy, frequently are difficult to turn and require special locking devices to prevent the lashing loosening due to rotation of an adjuster. As the ship travels and the loads shift the turnbuckles may be subjected to high forces (they have a 24 Tonne working load). Frequently this results in the thread of the turnbuckle “locking” which requires the stevedore to use a prise bar or the like to release the tension on the lashing rod. This process can affect turnbuckle thread life but more importantly leads to dangerous acts of striking and forcing followed by a sudden movement of the turnbuckle. This in turn can lead to off-balance falls, striking injuries and it is not uncommon for prise bars to fly off the turnbuckle when pushed or struck.
It is known that lashing is meant to be set with no slack but minimal tension. Excessive tension merely loads the container in a vertical direction leading to reduced load capacity or failure of a container due to excessive loading. Containers are regularly lost overboard through “stack collapse” with over tensioned lashing being a known contributor. Some lashing systems include a short tensioning spanner to try and restrict over tensioning but stevedores are known to use prise bars in their work which can over load the fittings. In addition, the tension applied is highly subjective with no real objective standard for knowing what is a “correct” tension. Once lashing is set it is generally required that it be rechecked after 24 hours at sea and also before encountering heavy weather. This can be a difficult task. Some manufacturers provide “quick slack removers” but these do not adequately address tension. The whole issue of compliance to re-tensioning requirements is almost impossible to validate. Even if a ship's captain is diligent in requiring crew to check lashing, they have little or no objective evidence that it has been done correctly (or at all) the same issue arises for owners and insurers. Quality assurance on lashing is almost non-existent.
In summary, existing lashing is difficult to individually identify or check. This leads to situations where the age and service life of a component is not known and a “fix on fail” style of repair is used. This can lead to failure in service and potentially risk to cargo, ships and workers. Turnbuckles are frequently over greased as well. This can lead to excessive grease covering workers and getting on the deck resulting in a very slippery floor and a hazardous workplace. It is also readily transferred to other equipment and handrails making them slippery and potentially dangerous. Current lashing bars are designed to hook into the corner casting of a container and then “lock in” when rotated into the operating position. A frequent issue is when a bar is “hung” temporarily. If the bar is touched or knocked it can readily fall out. Although hanging bars are not encouraged in many ports it occurs frequently and results in striking injuries. The current need to lower the long rods to the deck represents a constraint on how close together teams can work together. Adding extra workers to the lashing task regularly results in higher levels of adverse interaction between teams. This often takes the form of a worker from one team inadvertently striking or impeding workers form another team.
Accordingly there is a need to greatly reduce the amount of time and effort required to load and unload objects from structures such as the decks of ships. There is also a need to reduce the chance of injury to workers loading and unloading objects onto and off those structures.